Electric circuit with multiple nonlinear dielectric element



y 0, 1967 A. GLANC 3,323,084

ELECTRIC CIRCUIT WITH MULTIPLE NON-LINEAR DIELECTRIC ELEMENT Filed March 2, 1964 INVENTOR ANTONIN ANC BY ttorney United States Patent 3,323,084 ELECTRIC CIRCUIT WITH MULTIPLE NON- LINEAR DIELECTRIC ELEMENT Antonin Glanc, Lihochovice, Czechoslovakia, assignor to Ceskoslovenska akademie ved, Prague, Czechoslovakia, a corporation of Czechoslovakia Filed Mar. 2, 1964, Sen-No. 348,689 Clauns priority, application Czechoslovakia, Mar. 7, 1963, 1,298/63; Mar. 15, 1963, 1,472/63, 1,473/63 2 Claims. (Cl. 334-11) The invention relates to electric circuits with a nonlinear dielectric element which possesses a region in which the characteristic of the dielectric constant drops with temperature, the said element being heated by dielectric losses into the region of maximum non-linearities and maintained in this region by an autostabilization mode of operation which has been disclosed in patent application Ser. No. 318,302.

This patent application describes in great detail the mode of operation in which the dielectric is operated and gives a detailed analysis of these operational conditions and an account of its advantages. An example has also been described of using the said element in a dielectric amplifier of current design.

The advantages of the autostabilization mode of operation are, on the one hand, independence of ambient temperature and, on the other hand, the fact that at the autostabilized temperature the dielectric possesses the most pronounced non-linearities and that it is also free of electric hysteresis so that the respective electric circuits can be operated with considerable gain and without frequency limitation.

However, in some applications it is a drawback that the alternating voltage required for heating the dielectric to the stabilized temperature is too large so that it may interfere with the operation of the respective signal circuit.

The general object of this invention is to remove or substantially suppress this drawback and to create an element which can limit said undesirable effects of the heating voltage.

Briefly stated, the more specific object of this invention is an electric circuit with a multiple non-linear dielectric element the dielectric of which possesses a region in which the characteristic of the dielectric constant drops with temperature, the said element comprising at least one body made of a dielectric which possesses a maximum of at least the imaginary component of the dielectric constant, the said body being provided 'with two heating e ectrodes connected to the heating source, and the said element comprising further at least one other body made of a dielectric which possesses a maximum of at least the real component of the dielectric constant, the two maxima occurring at the same temperature and having a similar course, the said two types of bodies being in close thermal contact. Suitable electrodes of two adjacent bodies may coincide.

A further object of the invention is an electric circuit with the said multiple element forming a modulator or amplifier.

The invention will be best understood from the following specification to be read in conjunction with the ac companying drawing illustrating several preferred examples of embodying the invention. In the drawing:

FIG. 1 shows the arrangement of a multiple dielectric element in accordance with the invention with two bodies;

FIG. 2 is a similar arrangement as illustrated in FIG. 1, comprising three bodies;

FIG. 3 is the circuit arrangement of a frequency modulated oscillator with a dielectric element in accordance with the invention;

3,323,084 Patented May 30, 1967 FIG. 4 shows the circuit arrangement of a dielectric amplifier with a dielectric element in accordance with the invention.

The fundamental structural combination of two bodies of a non-linear dielectric will be explained with particular reference to FIG. 1 where 1 is the signal body of the non-linear dielectric element, 111, 112 are the electrodes thereof with the relevant leads, 2 is the heating body of the non-linear dielectric element, and 112, 113 are the electrodes thereof with the relevant leads.

The electrodes 112 and 113 are supplied with alternating high-frequency voltage for dielectric heating of the body 2 into the point of autostabilization of the temperature. The body 1 is in good thermal contact with the body 2, this contact being achieved by the electrodes common to both bodies so that the body 1 reaches the same temperature and thus also the region of maximum nonlinear properties. The electrodes 111 and 112 of the body are supplied with the signal voltage which has to be treated.

It should be noted that such pairs of non-linear elements have already been disclosed earlier but for a completely different purpose and with a different function. They have been used as a symmetrical three-pole capacitor connected in parallel to the inductance of the resonant circuit 50 that both bodies 1 and 2 have performed the same function. These bodies have also been always made of the same material.

The pair of non-linear elements used for the purpose of this invention has to meet another object, namely: at least one of the two bodies, in the present case body 2, is arranged in the circuit of the heating source and serves for indirect dielectric heating of the remaining signal body or bodies 1.

In view of the different functions which the two bodies perform in the arrangement according to the invention, both of them, that is the signal body 1 and the heating body 2, need not be made of the same material. It is essential that the material of the heating body 2 possesses a region in which the imaginary component of the dielectric constant possesses a dropping characteristic, and that the material of the signal body 1 possesses in this region the maximum of the characteristic of the real component of the dielectric constant, and therefore also a maximum of dielectric non-linearities. As disclosed in the abovenoted copending application, a suitable material is triglycin sulphate.

FIG. 2 shows another possible constructional modification of the invention. In this figure, 1 is the signal body of the non-linear dielectric element, 112 and 114 are the electrodes and leads of this body, 21 and 22 are heating bodies of the non-linear dielectric element, and 113 and 115 are their electrodes and leads thereto.

The advantage of this modification resides in a better temperature efficiency because the signal body 1 is heated from both sides.

It should be obvious to those expert in the art that the number of bodies employed to create an element in ac-' cordance with the invention is not limited to two and may even exceed three. In fact, the number of bodies used depends on the type of circuit arrangement in which such an element is employed, as will be explained in more detail below.

FIG. 3 shows an example of a circuit arrangement in accordance with the invention which represents a simplified fundamental frequency modulated oscillator circuit.

In this figure, 38 is the oscillator tube, 31 is the grid coil, 33 is the separating capacitor, 1 is the signal body of a multiple non-linear electrical element forming together with 33 and 31 the grid circuit, 32 and 34 are members of a feedback circuit, 36 and 37 are members of the grid circuit of the tube 38 and 39 denotes the output transformer. The body 2 for dielectric heating is connected through the regulating capacitor 8 for full oscillator voltage. The signal body 1 is connected through a separating choke 10 with the source of modulating signal 9 and, if required, also with the source of the direct-current polarization voltage through a separating resistor 35.

The fundamental function of such an oscillator is known. The tube 38 works as a feedback oscillator in which part of the capacity of the resonant circuit is formed by the dielectric body 1. Since the capacity of the element 1 depends on the voltage applied, this capacity changes; and with it also within certain limits, the oscillator frequency is modulated by the signal voltage 9. The capacitors 33 and the signal body 1 acting as capacitor act as direct-current blocking elements of the polarization and modulation voltages from the oscillation circuit.

If the non-linear dielectric element included only the signal body 1, as just described, it would operate at a temperature which would not quite differ from the ambient temperature and would therefore vary in agreement with the latter. This would also cause a variation of the quies cent capacity of the dielectric element and in consequence thereof, the medium frequency of the oscillator would also vary. Moreover, at this temperature the element would possess unfavourable electric properties so that the frequency deviation obtained would be rather small. These properties cannot be improved in the given case by introducing'direct electric heating of the body 1 in accordance with the above mentioned patent application Ser. No. 318,302 due to the fact that the grid circuit of the tube does not comprise sufficient alternating voltage and such a large voltage cannot be introduced from the outside without seriously endangering the total operation of the oscillator. Therefore, in accordance with the invention, there is arranged in thermal contact with the body 1 another body 2 made of a non-linear dielectric. The voltage in the anode circuit is suificient for electric heating, and dueto the fact that the two bodies 1 and 2 are in good thermal contact via their common electrode, the body 1 reaches the same temperature as the body 2, this temperature being stabilized just in the region of the most favourable electric properties. Due to the fact the two bodies 1 and 2 are grounded via their common electrode, the voltage is not transferred from the heating body 2 to the body 1, and further into the signal circuit. The circuit arrangement according to FIG. 2 is stable both with regard to voltage and temperature. It is particularly adapted for those cases in which further amplification of the obtained frequency is required.

FIG. 4 shows the circuit arrangement of a dielectric amplifier in accordance with the invention. In this figure, 4 denotes the source of high-frequency voltage and 8 is a regulation capacitor for heating control connected to the outer electrodes of the heating bodies 21 and 22 respectively, of the multiple element 11 and 12 are the sigrial bodies of this dielectric element between whose central electrodes and one outer electrodes is connected a signal source 9 through a choke 10. To the second and fourth electrode of the element is connected an inductance 7 forming with the capacity of the signal bodies 11 and 12 a resonant circuit which is connected with an output demodulator 100, 101, 102. If necessary, the source 5 of a direct-current polarization voltage may also be connected in the circuit.

The bodies 11 and 12 are here again used for the signal circuit and they work so that their capacity is changed by the signal voltage of the source 9. This causes mistuning of the circuit 7, 11, 12 with regard to the frequency of the high-frequency heating source 4 so that a high-frequency voltage is produced across the inductance 7, this voltage being amplitude modulated at the rhythm of the signal. This voltage'is then demodulated by the diode 100 and an amplified signal is created across the rectifying member 101 and 102. This known function is improved in accordance with the invention by means of further bodies 21 and 22 which are arranged in the circuit of the high-frequency heating source 4 so that they become heated into the autostable state by dielectric heating. The temperature of the said bodies 21 and 22 is also indirectly imparted to the signal bodies 11 and 12 which thus reach the temperature at which their electric properties are most favourable. The heating body 21 has in this case also another function. It blocks the polarization bias source 5 against ground and it also grounds the lower end of the resonant circuit 7, 11, 12 for high-frequency voltage.

The electric circuit illustrated in FIGS. 3 and 4 show examples of how the invention may be usefully employed but do not exhaust the full scope of the invention.

What I claim is:

1. An electric circuit comprising four dielectric elements, each of said dielectric elements having a dielectric material the permittivity of which varies with tempera ture, first electrode means common to adjacent dielectric elements and connecting said elements'in series, second electrode means positioned on the external ones of said dielectric elements, the internal dielectric elements form- 1 tric losses are in equilibrium with heat dissipated into ambient space, a signal source connected to one of said common electrodes of said first electrode means between the internal dielectric elements and to one of said second electrode means, an inductor connected to two of said common electrodes of said first electrode means between said external and said internal dielectric elements, said inductor forming with said internal dielectric elements a tuned circuit, and an output connected to said tuned circuit.

2. An electric circuit comprising a first and a second dielectric element, each of said dielectric elements having a dielectric material, the permittivity of which varies with temperature, a common electrode connecting said dielectric elements for close thermal contact, an external electrode positioned on each of said dielectric elements, the dielectric material of said first dielectric element forming with its external electrode and said common electrode a capacitor as part of said electric circuit, the dielectric material of the second dielectric element comprised of a material with a permittivity having a dropping characteristic at temperatures above its Curie point, an alternating current heating source connected between the external electrode of said second dielectric element and said common electrode, said second dielectric element maintained by said alternating current heating source by dielectric losses at a temperature above its Curie point in a temperature autostabilized state Where dielectric losses are in equilibrium with heat dissipated into ambient space.

References Cited UNITED STATES PATENTS 2,484,636 10/1949 Mason 332-30 2,788,446 4/ 1957 Cerveny et al 332-30 X 3,050,638 8/1962 Evans et al. 307-88.5 3,210,607 10/ 1965 Flanagan 317262 ROY LAKE, Primary Examiner. ALFRED L. BRODY, Examiner. 

1. AN ELECTRIC CIRCUIT COMPRISING FOUR DIELECTRIC ELEMENTS, EACH OF SAID DIELECTRIC ELEMENTS HAVING A DIELECTRIC MATERIAL THE PERMITTIVITY OF WHICH VARIES WITH TEMPERATURE, FIRST ELECTRODE MEANS COMMON TO ADJACENT DIELECTRIC ELEMENTS AND CONNECTING SAID ELEMENT IN SERIES, SECOND ELECTRODE MEANS POSITIONED ON THE EXTERNAL ONES OF SAID DIELECTRIC ELEMENTS, THE INTERNAL DIELECTRIC ELEMENTS FORMING TOGETHER WITH SAID FIRST ELECTRODE MEANS CAPACITORS, SAID EXTERNAL DIELECTRIC ELEMENTS COMPRISING A MATERIAL WITH A PERMITTIVITY HAVING A DROPPING CHARACTERISTIC AT TEMPERATURES ABOVE THEIR CURIE POINT, AN ALTERNATING CURRENT HEATING SOURCE CONNECTED TO SAID SECOND ELECTRODE MEANS FOR MAINTAINING SAID EXTERNAL DIELECTRIC ELEMENTS BY DIELECTRIC LOSSES AT TEMPERATURES ABOVE THEIR CURIE POINT IN A TEMPERATURE AUTOSTABILIZED STATE, WHERE DIELECTRIC LOSSES ARE IN EQUILIBRIUM WITH HEAT DISSIPATED INTO AMBIENT SPACE, A SIGNAL SOURCE CONNECTED TO ONE OF SAID COMMON ELECTRODES OF SAID FIRST ELECTRODE MEANS BETWEEN THE INTERNAL DIELECTRIC ELEMENTS AND TO ONE OF SAID SECOND ELECTRODE MEANS, AN INDUCTOR CONNECTED TO TWO OF SAID COMMON ELECTRODES OF SAID FIRST ELECTRODE MEANS BETWEEN SAID EXTERNAL AND SAID INTERNAL DIELECTRIC ELEMENTS, SAID INDUCTOR FORMING WITH SAID INTERNAL DIELECTRIC ELEMENTS A TURNED CIRCUIT, AND AN OUTPUT CONNECTED TO SAID TUNED CIRCUIT. 